1. Field of the Invention
The present invention relates generally to catheters, and in particular to catheters that can be used to assist in removal of items endovascularly.
2. Description of the Related Art
Inferior vena cava filters (“IVC filters”) are medical devices that can be implanted into the inferior vena cava to prevent pulmonary emboli (PE). IVC filters are sometimes recommended for patients with contraindications to anticoagulation who either have acute PE or acute proximal (above the knee) deep vein thrombosis. IVC filters are normally placed by compressing them into a thin catheter, and inserting them via a blood vessel, such as the femoral vein, the internal jugular vein, or the arm veins. Once the distal end of the catheter reaches the IVC, the IVC filter is pushed through the catheter and deployed into the desired location.
IVC filters are typically attached to the vena cava by hooks on their ends. Some IVC filters are compression springs, which compress outward onto the sidewall of the vena cava; however, they still have small hooks that retain their location. These hooks aid in the anchoring and healing process, but they make it difficult to retrieve the IVC filter from the vena cava.
FIG. 1 shows an IVC filter 1 deployed in the inferior vena cava. IVC filters 1 are generally anchored by anchors 4 to prevent them from migrating. IVC filters 1 are removed by using a snare 2 and a retrieval sheath 3. Coupling the snare with the IVC filter 1 is difficult. The IVC filter 1 may not be vertically aligned making it difficult to snare. Body movement due to respiration and blood flow also make snaring the IVC filter 1 difficult.
As can be seen in FIG. 1, the snare 2 is attached to the top of the filter 1. As shown in FIG. 2, the sheath 3 is pushed down over the filter 1, capturing the filter 1 and its contents and removing the filter anchors 4 from the vein wall. This allows the filter 1 to be removed. However, on occasion the filter anchors 4 or a portion of the filter 1 become embedded to the vein wall, and this removal procedure cannot be performed.
There is a need for an improved tool to assist with the removal of IVC filters.